Messages - dougkerr

Hi,I own a Canon 450D at present but am waiting for the next release of the 5D.In the meantime I'd like to buy a lens which would hopefully fit both. Is the Canon EF 85mm f/1.2L II USM compatible with both cameras?

Absolutely.

Note that when the lens is used on an EOS 5D, because of its larger sensor size than that of the 450D, the field of view will be greater.

â€¢ If the lens is not intended to be used on "full-frame 35-mm size" sensor cameras, but rather those with a smaller sensor size, it can have a smaller image circle, and this makes it easier to design for a certain set of optical properties with a certain optical performance.

â€¢ If the lens is not intended to be used "full-frame 35-mm size" sensor cameras, but rather those with a smaller sensor size (and thus a smaller reflex mirror, assuming an SLR arrangement), then the lens can have a smaller "back focus" (the physical distance from the rearmost point on the lens to the focal plane), which simplifies the design of lenses with smaller focal lengths.

Overall, then, we might expect that the objective is to allow the design of lenses for use only on "smaller-format" cameras that are less costly, smaller, and/or lighter, for given optical properties and optical performance, than if they were designed to be used on all cameras of the genre, including those with a full-frame 35-mm sensor size.

Note that the focal length quoted for EF-S lenses is (nominally) the "actual" focal length of the lens (the only focal length it has). It is an optical property of the lens, and does not presuppose its use in any particular format size camera . The lens has that property on any camera it will fit, or when in its carton.

The stating of the "full-frame 35-mm equivalent focal length" for a lens as it will be used on a camera of some particular format size, other than "full-frame 35-mm", is intended to allow the real property of interest, the field of view of the lens when used on that camera, to be expressed in a familiar, traditional form which can be compared to work with a full-frame 35-mm format camera. It is not an actual focal length of the lens under any circumstances.

My understanding of RAW is that it is simply the data "as-is" read from the sensor and saved on the memory card with no processing applied. However, I found that the color temp as set in a 50d directly affects the color temp of the saved RAW image. Are other in-camera functions applied to RAW as well?

The white balance color correction setting in the camera does not have any effect on the raw data.

However, that setting is saved (in a technically-detailed way) in the metadata of the raw file.

Then, when the raw data is "developed" in external software to a JPEG or TIFF file, color correction is then applied, as set by the operator in any of various ways. One option is for the operator to tell the software to use the color correction that was set in the camera (which the software can read from the metadata) - the same color correction that the camera would have (or did) use in the in-camera generation of a JPEG file for the shot. But that is an explicit choice by the operator.

Chuck Westfall of Canon USA has recently advised of a correction to his original summary of the circumstances in which the Speedlite 430EX (and 430EX II) flash units may operate in the multi-flash ("stroboscopic") mode.

He had originally said that the units could operate in that mode only when operating as a slave and the master is a Speedlite 550EX, 580EX, or 580EX II or the onboard flash unit of an EOS 7D.

He now advises that he has determined that in fact the multi-flash mode cannot be utilized by way of the onboard flash unit of an EOS 7D as a master. When that facility is set to the multi-flash mode, its operation as a master is disabled.

Thus, the Speedlite 430EX (or 430EX II) can only operate in the multi-flash mode when operating as a slave and the master is a Speedlite 550EX, 580EX, or 580EX II.

Again, to avert any misunderstanding, the 430EX (or 430EX II) apparently cannot provide the multi-flash mode when being directly operated from any camera, whether or not that camera provides for setting the associated flash.